Treatment of animal carcasses

ABSTRACT

Described is a method of sanitizing animal carcasses using aqueous streams having an antimicrobial composition added to the stream. Preferably, the antimicrobial composition includes a mixture of one or more carboxylic acids having up to 18 carbon atoms and one or more peroxycarboxylic acids having up to 12 carbon atoms, preferably a mixture of a C 2 -C 4  peroxycarboxylic acid and a C 8 -C 12  peroxycarboxylic acid. Also described is a novel antimicrobial composition adapted for sanitizing animal carcasses containing a mixture of one or more C 2 -C 4  peroxycarboxylic acids and one or more C 8 -C 12  peroxycarboxylic acids and an alpha-hydroxy mono- or dicarboxylic acid.

FIELD OF THE INVENTION

[0001] This invention generally relates to compositions and processesfor cleaning or sanitizing animal carcasses during meat packing orpreparation. More specifically, this invention relates to antimicrobialcompositions and processes for cleaning and sanitizing animal carcassestrough direct contact between the carcass and the treatment. The natureof the contact between the carcass and the antimicrobial compositionsimproves antimicrobial properties. The compositions and methods reducemicrobial populations and do not affect the appearance, smell or tasteof the carcass meat.

BACKGROUND OF THE INVENTION

[0002] The cleaning of carcasses in the preparation of any food productcan be an unsanitary and time consuming task. Further, without acleaning routine which follows an ordered process of steps to completelysanitize carcass meat, any number of problems may arise. Carcass meatmay retain pathogens or infectious microbes (E. coli) or becomeincreasingly more contaminated if viscera is allowed to rupture or isnot properly removed. Further, incomplete cleaning of the carcass meatmay also result in the presence of infectious microbes making the meatunsuitable for consumption.

[0003] PURAC® is a natural lactic acid produced by fermentation fromsugar. It has a mild acid taste and is widely used in the food industryas an acidulant. PURAC® is an effective decontaminating agent for usewith poultry, beef and pork carcasses and slaughter by-products. PURAC®is most effective at a use concentration of between 1 and 2 percent, andcan be used at several different points in the slaughter line.Application immediately after hide removal reduces the amount ofmicroorganisms entering subsequent processing steps, while treatmentsafter evisceration and prior to chilling have the greatest residualeffects. Mountney et al. also discuss the use of lactic acid to lowerbacterial counts and otherwise preserve poultry in “Acids As PoultryMeat Preservatives” in Poultry Science, 44: 582, 1965. Blankenship etal. discussed the destruction of Salmonella contaminates on fajitachicken meat in “Efficacy of Acid Treatment Plus Freezing To DestroySalmonella Contaminates Of Spice Coated Chicken Fajita Meat” in PoultryScience, Vol. 69, Supp., 1990, p. 20. Adams et al. discuss the use ofpropylene glycol, sodium lactate, and lactic acid in chill water toreduce salmonella contamination of processed broilers. (See, Effects ofVarious Chill Water Treatments on Incidents and Levels of Salmonella onProcessed Carcasses, Department of Animal and Poultry Sciences,University of Arkansas, Fayetteville). Izat et al. discuss the effectsof lactic acid on commercial broiler carcasses in reducing salmonellacounts in Poultry Science, Vol. 69, Supp. 1990, p. 152; Journal ofQuality, Vol. 13, 1990 p. 295-306; and Journal of Food Protection, Vol.52, No. 9, pp. 670-673, September 1989. Avens et al. discuss thepasteurization of turkey carcasses and the reduction of salmonella usinglactic acid in Poultry Science, Vol. 51, 1972, p. 1781. Mulder et al. in1987 Poultry Science 66:1555-1557 reports a study of treating broilercarcasses with lactic acid, 1-cysteine and hydrogen peroxide. Thetreatment with lactic acid and hydrogen peroxide resulted in a 4-logcycle reduction in colony forming units of Salmonella typhimurium.Nevertheless, use of lactic acid resulted in a slightly changed color ofthe carcasses and all the treatments with hydrogen peroxide resulted inbleached and bloated carcasses.

[0004] Although peroxycarboxylic acids are known to be used for cleaningand sanitizing equipment and other surfaces, they have not been reportedfor cleaning and sanitizing animal carcasses. Holzhauer et al., U.S.Pat. No. 5,435,808, describes curing of animal hides with an aceticacid, peroxyacetic acid, hydrogen peroxide, and phosphoric acidcombination. The heightened concerns of consumers over the organolepticpurity and safety of meat products, concerns over the environmental andorganoleptic impact of many antimicrobial agents currently available, aswell as the stringent economies of the meat and poultry industry haveresulted in an ongoing need for carcass sanitizing compositions andprocesses which provide increased sanitization with organoleptic andenvironmental purity.

SUMMARY OF THE INVENTION

[0005] Accordingly the present invention, in a first aspect, provides amethod of treating animal carcasses to obtain a reduction by at leastone log₁₀ in surface microbial population which method includes the stepof treating said carcass with an antimicrobial composition comprising aneffective antimicrobial amount comprising at least 2 parts per million(ppm, parts by weight per each one million parts) of one or moreperoxycarboxylic acids having up to 12 carbon atoms and an effectiveantimicrobial amount comprising at least 20 ppm of one or morecarboxylic acids having up to 18 carbon atoms to reduce the microbialpopulation.

[0006] A second aspect of the invention is an antimicrobial compositionadapted for cleaning and sanitizing animal carcasses which containsabout 0.5 weight percent (wt-%) to about 20 wt-% of a mixture of one ormore peroxycarboxylic acids having from 2-4 carbon atoms, and one ormore peroxycarboxylic acids having from 8-12 carbon atoms, from about0.5 wt-% to about 60 wt-% of an alpha-hydroxy mono or dicarboxylic acidhaving 3-6 carbon atoms, an effective amount of a sequestrant and aneffective amount of a hydrotrope.

[0007] A third preferred aspect of the present invention is anantimicrobial composition adapted for treating animal carcassesconsisting of a mixture of peroxyacetic and peroxyoctanoic acid in aratio of about 10:1 to about 1:1, from about 0.1 to about 10 wt-% oflactic acid, from about 4 wt-% to about 10 wt-% of hydrogen peroxide andfrom about 0.5 wt-% to about 1.5 wt-% of a sequestering agent.

[0008] A fourth aspect of the present invention involves a method oftreating an animal carcass to reduce a microbial population in resultingcut meat, the method comprising the steps of spraying an aqueousantimicrobial treatment composition onto said carcass at a pressure ofat least 50 psi at a temperature of up to about 60° C. resulting in acontact time of at least 30 seconds, the antimicrobial compositioncomprising an effective antimicrobial amount comprising least 2 ppm ofone or more carboxylic acid, peroxycarboxylic acid or mixtures thereof;and achieving at least a one log₁₀ reduction in the microbialpopulation.

[0009] A fifth aspect of the present invention involves a method oftreating an animal carcass to reduce a microbial population in resultingcut meat, the method comprising the steps of placing the carcass in achamber at atmospheric pressure; filling the chamber with condensingsteam comprising an antimicrobial composition for a short duration; andquickly venting and cooling the chamber to prevent browning of the meatcarcass; wherein the duration of the steam thermal process may be fromabout 5 seconds to about 30 seconds and the chamber temperature mayreach from about 50° C. to about 93° C.

[0010] The antimicrobial composition can be applied in various ways toobtain intimate contact with each potential place of microbialcontamination. For example, it can be sprayed on the carcasses, or thecarcasses can be immersed in the composition. Additional methods includeapplying a foamed composition and a thickened or gelled composition.Vacuum and or light treatments can be included, if desired, with theapplication of the antimicrobial composition. Thermal treatment can alsobe applied, either pre-, concurrent with or post application of theantimicrobial composition. We have found a preferred spray method fortreating carcasses with compositions of the invention involving sprayingthe carcass with an aqueous spray at a temperature less than about 60°C. at a pressure of about 50 to 500 psi gauge wherein the spraycomprises an effective antimicrobial amount of a carboxylic acid, aneffective antimicrobial amount of a peroxycarboxylic acid or mixturesthereof. These sprays can also contain an effective portion of a peroxycompound such as hydrogen peroxide and other ingredients such assequestering agents, etc. We have found that the high pressure sprayaction of the aqueous treatment removes microbial populations bycombining the mechanical action of the spray with the chemical action ofthe antimicrobial materials to result in a surprisingly improvedreduction of such populations on the surface of the carcass. Allpressures are psig (or psi gauge). Differentiation of antimicrobial“-cidal” or “-static” activity, the definitions which describe thedegree of efficacy, and the official laboratory protocols for measuringthis efficacy are important considerations for understanding therelevance of antimicrobial agents in compositions. Antimicrobialcompositions may effect two kinds of microbial cell damages. The firstis a truly lethal, irreversible action resulting in complete microbialcell destruction or incapacitation. The second type of cell damage isreversible, such that if the organism is rendered free of the agent, itcan again multiply. The former is termed bacteriocidal and the latter,bacteriostatic. A sanitizer and a disinfectant are, by definition,agents which provide antibacterial or bacteriocidal activity and achieveat least a five fold reduction (i.e., a five log10 reduction) inmicrobial populations after a 30 second contact time (see AOAC method960.09).

[0011] In contrast, a preservative is generally described as aninhibitor or bacteriostatic composition that simply retards growth in areversible mode. For the purpose of this patent application, successfulmicrobial reduction is achieved when the microbial populations arereduced by one log₁₀. In this industry, the one log₁₀ microbialpopulation reduction is the minimum acceptable for the processes. Anyincreased reduction in microbial population is an added benefit thatprovides higher levels of protection for processed carcass meat.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The invention is a process for sanitizing animal carcassesthrough treatment with aqueous streams containing an antimicrobialcomposition. The dip or spray methods used for carcass cleaning as wellas sanitizing animal carcasses generally include an effectiveantimicrobial concentration of one or more carboxylic acids and one ormore peroxycarboxylic acids.

[0013] A. The Sanitizing Composition

[0014] The sanitizing composition used in the method of the inventiongenerally contains one or more carboxylic acids and one or moreperoxycarboxylic acids with a peroxygen compound such as H₂O₂.Typically, however, the composition contains one or more carboxylicacids, an oxidizer, and one or more peroxycarboxylic acids depending onequilibrium. Commonly, the peroxycarboxylic acid material can be made byoxidizing a carboxylic acid directly to the peroxycarboxylic acidmaterial which is then solubilized in the aqueous rinse agentcompositions of the invention. Further, the materials can be made bycombining the unoxidized acid with a peroxygen compound such as hydrogenperoxide to generate the peracid in situ prior to blending theperoxycarboxylic acid with other constituents. The compositions of theinvention comprises blends of the carboxylic acid and percarboxylic acidalong with other components including a peroxy source such as hydrogenperoxide. Once blended and applied the compositions can change due tointeractions between the blended materials and due to interactions inthe use locus. For example, the salt component can exchange and becomeassociated with free acids and the peroxy source can oxidize oxidizablematerials. The anti-microbial properties arise from the blend of an acidmaterial and a peracid material. The modification post blending andapplication do not change the invention.

[0015] A carboxylic acid is an organic acid (R—COOH) which contains analiphatic group and one or more carboxyl groups. A carboxyl group isrepresented by —COOH, and is usually located at a terminal end of theacid. The aliphatic group can be a substituted or unsubstituted group.Common aliphatic substituents include —OH, —OR, —NO₂, halogen, and othersubstituents common on these groups. An example of a simple carboxylicacid is acetic acid, which has the formula CH₃COOH. A peroxycarboxylicacid is a carboxylic acid which has been oxidized to contain a terminal—COOOH-group. The term peroxy acid is often used to represent aperoxycarboxylic acid. An example of a simple peroxy acid isperoxyacetic acid, which has the formula CH₃COOOH. Generally when theperoxycarboxylic acid is formulated in accordance with the invention amonocarboxylic acid, such as acetic acid, is combined with an oxidizersuch as hydrogen peroxide. The result of this combination is a reactionproducing a peroxycarboxylic acid, such as peroxyacetic acid, and water.The reaction follows an equilibrium in accordance with the followingequation:

H₂O₂+CH₃COOH

CH₃COOOH+H₂O

[0016] wherein the pK_(eq) is 1.7.

[0017] The importance of the equilibrium results from the presence ofhydrogen peroxide, the carboxylic acid and the peroxycarboxylic acid inthe same composition at the same time. Because of this equilibrium, amixture of carboxylic acid and peroxycarboxylic acid can be combined inwater without adding hydrogen peroxide. If permitted to approachequilibrium, the mixture will evolve hydrogen peroxide. This combinationprovides enhanced sanitizing with none of the deleterious environmentalor organoleptic effects of other sanitizing agents, additives, orcompositions.

The Carboxylic Acid

[0018] The first constituent of the composition used in the method ofthe invention includes one or more carboxylic acids. Generally,carboxylic acids have the formula R—COOH wherein the R may represent anynumber of different groups including aliphatic groups, alicyclic groups,aromatic groups, heterocyclic groups, all of which may be saturated orunsaturated. Carboxylic acids also occur having one, two, three, or morecarboxyl groups. Aliphatic groups can be further differentiated intothree distinct classes of hydrocarbons. Alkanes (or paraffins) aresaturated hydrocarbons. Alkenes (or olefins) are unsaturatedhydrocarbons which contain one or more double bonds and alkynes (oracetylenes) are unsaturated hydrocarbons containing one or more highlyreactive triple bonds. Alicyclic groups can be further differentiatedinto three distinct classes of cyclic hydrocarbons. Cycloparaffins aresaturated cyclic hydrocarbons. Cycloolefins are unsaturated cyclichydrocarbons which contain one or more double bonds whilecycloacetylenes are unsaturated cyclic hydrocarbons containing one ormore highly reactive triple bonds. Aromatic groups are defined aspossessing the unsaturated hydrocarbon ring structure representative ofbenzene. Heterocyclic groups are defined as 5 or 6 member ringstructures wherein one or more of the ring atoms are not carbon. Anexample is pyridine, which is essentially a benzene ring with one carbonatom replaced with a nitrogen atom.

[0019] Carboxylic acids have a tendency to acidify aqueous compositionsin which they are present as the hydrogen atom of the carboxyl group isactive and may appear as a cation. The carboxylic acid constituentwithin the present composition when combined with aqueous hydrogenperoxide generally functions as an antimicrobial agent as a result ofthe presence of the active hydrogen atom. Moreover, the carboxylic acidconstituent within the invention maintains the composition at an acidicpH. The composition of the invention can utilize carboxylic acidscontaining as many as 18 carbon atoms. Examples of suitable carboxylicacids include formic, acetic, propionic, butanoic, pentanoic, hexanoic,heptanoic, octanoic, nonanoic, decanoic, undecanoic, dodecanoic, lactic,maleic, ascorbic, citric, hydroxyacetic, neopentanoic, neoheptanoic,neodecanoic, oxalic, malonic, succinic, glutaric, adipic, pimelic andsubric acid.

[0020] Carboxylic acids which are generally useful are those having oneor two carboxyl groups where the R group is a primary alkyl chain havinga length of C₂ to C₅ and which are freely water soluble. The primaryalkyl chain is that carbon chain of the molecule having the greatestlength of carbon atoms and directly appending carboxyl functionalgroups. Especially useful are mono- and dihydroxy substituted carboxylicacids including alpha-hydroxy substituted carboxylic acid. A preferredcarboxylic acid is acetic acid, which produces peroxyacetic acid toincrease the sanitizing effectiveness of the materials. Acetic acid hasthe structure of the formula:

[0021] An especially preferred α-hydroxy-monocarboxylic acid is lacticacid, also known as 2-hydroxypropionic acid, which is a naturallyoccurring organic acid. Lactic acid has a molecular weight of 90.08 andis soluble in water, alcohol, acetone, ether and glycerol. Lactic acidoccurs naturally and may be produced by fermentation. Alternatively,lactic acid may be synthesized.

[0022] Lactic acid has the structure of the formula

[0023] The concentration of α-hydroxy-mono-or di-carboxylic acid usefulin the present invention generally ranges from about 0.5 wt-% to about60 wt-%, preferably about 1 wt-% to about 20 wt-%, and most preferablyfrom about 2 wt-% to about 10 wt-%. This concentration range of lacticacid is preferred for reasons of optimal acidity within the composition,as well as for the optimal antimicrobial efficacy which it brings to theantimicrobial system.

[0024] Reducing the concentration of lactic acid in comparison to anygiven concentration of hydrogen peroxide will essentially reduce theantimicrobial activity of the composition. Moreover, reducing theconcentration of lactic acid may result in an increase in the pH of thecomposition and accordingly raise the potential for decreasedantimicrobial activity. In sharp contrast, increasing the concentrationof lactic acid within the present composition may tend to increase theantimicrobial activity of the composition. Furthermore, increasing theconcentration of lactic acid in the composition of the present inventionwill tend to decrease the pH of the composition. Preferably, the pH ofthe present composition will be 4 or less with a generally preferred pHin the composition being between 1.5 and 3.75, and a pH between about 2and 3.5 being most preferred.

[0025] Generally, the concentration of carboxylic acid within thecomposition used in the process of the invention ranges from about 0.5wt-% to about 60 wt-%, preferably from about 10 wt-% to about 60 wt-%,and most preferably from about 20 wt-% to about 50 wt-%.

The Peroxycarboxylic Acid

[0026] Another principle component of the antimicrobial composition ofthe invention is an oxidized carboxylic acid. This oxidized orperoxycarboxylic acid provides heightened antimicrobial efficacy whencombined with hydrogen peroxide and the monocarboxylic acid in anequilibrium reaction mixture. Peroxycarboxylic acids generally have theformula R(CO₃H)_(n), where R is an alkyl, arylalkyl, cycloalkyl,aromatic or heterocyclic group, and n is one or two and named byprefixing the parent acid with peroxy. An alkyl group is a paraffinichydrocarbon group which is derived from an alkane by removing onehydrogen from the formula. The hydrocarbon group may be either linear orbranched, having up to 12 carbon atoms. Simple examples include methyl(CH₃) and ethyl (CH₂CH₃). An arylalkyl group contains both aliphatic andaromatic structures. A cycloalkyl group is defined as a cyclic alkylgroup.

[0027] While peroxycarboxylic acids are not very stable, their stabilitygenerally increases with increasing molecular weight. Thermaldecomposition of these acids may generally proceed by free radical andnonradical paths, by photodecomposition or radical-induceddecomposition, or by the action of metal ions or complexes.Peroxycarboxylic acids may be made by the direct, acid catalyzedequilibrium action of 30-98 wt-% hydrogen peroxide with the carboxylicacid, by autoxidation of aldehydes, or from acid chlorides, acidanhydrides, or carboxylic anhydrides with hydrogen or sodium peroxide.

[0028] Peroxycarboxylic acids useful in this invention includeperoxyformic, peroxyacetic, peroxypropionic, peroxybutanoic,peroxypentanoic, peroxyhexanoic, peroxyheptanoic, peroxyoctanoic,peroxynonanoic, peroxydecanoic, peroxyundecanoic, peroxydodecanoic,peroxylactic, peroxymaleic, peroxyascorbic, peroxyhydroxyacetic,peroxyoxalic, peroxymalonic, peroxysuccinic, peroxyglutaric,peroxyadipic, peroxypimelic and peroxysubric acid and mixtures thereof.These peroxycarboxylic acids have been found to provide goodantimicrobial action with good stability in aqueous streams. In apreferred embodiment, the composition of the invention utilizes acombination of several different peroxycarboxylic acids. Preferably, thecomposition includes one or more small C₂-C₄ peroxycarboxylic acids andone or more large C₈-C₁₂ peroxycarboxylic acids. Especially preferred isan embodiment in which the small peroxycarboxylic acid is peroxyaceticacid and the large acid is either peroxyoctanoic acid or peroxydecanoicacid.

[0029] Peroxyacetic acid is a peroxycarboxylic acid with a structure asgiven the formula:

[0030] wherein the peroxy group, —O—O—, is considered a high energybond. Generally, peroxyacetic acid is a liquid having an acrid odor andis freely soluble in water, alcohol, ether, and sulfuric acid.Peroxyacetic acid may be prepared through any number of means known tothose of skill in the art including preparation from acetaldehyde andoxygen in the presence of cobalt acetate. A 50% solution of peroxyaceticacid may be obtained by combining acetic anhydride, hydrogen peroxideand sulfuric acid. Other methods of formulation of peroxyacetic acidinclude those disclosed in U.S. Pat. No. 2,833,813, which isincorporated herein by reference.

[0031] Peroxyoctanoic acid has the structure of the formula:

[0032] Peroxydecanoic acid has the structure of the formula:

[0033] The preferred peroxycarboxylic acid materials of the inventioncan be used to increase the sanitizing effectiveness of the materials.When a blended acid is used, the peroxycarboxylic acid is blended inproportions that range from about 10:1 to about 1:1 parts of C₂-C₄peroxyCarboxylic acid per part of C₈-C₁₂ peroxycarboxylic acid.Preferably, peroxyacetic acid is used at a ratio of about 8 parts perpart of peroxyoctanoic acid.

[0034] The above sanitizer material can provide antibacterial activityto the rinse aid sanitizers of the invention against a wide variety ofmicroorganisms such as gram positive (for example, Staphylococcusaureus) and gram negative (for example, Escherichia coli)microorganisms, yeast, molds, bacterial spores, viruses, etc. Whencombined, the above peroxy acids can have enhanced activity compared tothe low molecular weight peroxy acids alone.

[0035] Generally, the concentration of peroxycarboxylic acid within thecomposition used in the process of the invention ranges from about 0.5wt-% to about 20 wt-%, preferably from about 2 wt-% to about 15 wt-%,and most preferably from about 4 wt-% to about 12 wt-%.

The Oxidizer

[0036] The composition used in the method of the invention also includesan oxidizer. Any number of oxidizers may be used as a precursor to theformation of a peroxycarboxylic acid as well as to provide furtherphysical effervescent or agitation action to the composition of theinvention. Preferably, the antimicrobial composition of the inventioncontains hydrogen peroxide. Hydrogen peroxide (H₂O₂) has a molecularweight of 34.014 and it is a weakly acidic, clear, colorless liquid. Thefour atoms are covalently bonded in a non-polar structure:

[0037] Generally, hydrogen peroxide has a melting point of −0.41° C., aboiling point of 150.2° C., a density at 25° C. of 1.4425 grams per cm³,and a viscosity of 1.245 centipoise at 20° C.

[0038] Hydrogen peroxide in combination with the carboxylic acid andperoxycarboxylic acid provides a surprising level of antimicrobialaction against microorganisms, even in the presence of high loadings oforganic sediment Additionally, hydrogen peroxide provides aneffervescent action which may irrigate any surface to which it isapplied Hydrogen peroxide works with a mechanical flushing action onceapplied which further plains the surface of application. An additionaladvantage of hydrogen peroxide is the food compatibility of thiscomposition upon use and decomposition. For example, combinations ofperoxyacetic acid and hydrogen peroxide result in acetic acid, water,and oxygen upon decomposition. All of these constituents are foodproduct compatible. Generally, the concentration of hydrogen peroxidewithin the composition used in the process of the invention ranges fromabout 1 wt-% to about 35 wt-%, preferably from about 2 wt-% to about 25wt-%, and most preferably from about 5 wt-% to about 10 wt-%. Thisconcentration of hydrogen peroxide is most preferred as providingoptimal antimicrobial effect.

[0039] These concentrations of hydrogen peroxide may be increased ordecreased while still remaining within the scope of the presentinvention. For example, increasing the concentration of hydrogenperoxide may increase the antimicrobial efficacy of the claimedinvention. Furthermore, increasing the hydrogen peroxide concentrationmay reduce the need to stabilize the hydrogen peroxide within thecomposition. Specifically, increasing the hydrogen peroxideconcentration in the composition may provide a composition which hasextended shelf life.

[0040] In contrast, decreasing the concentration of hydrogen peroxidemay decrease the antimicrobial efficacy of the composition andnecessitate the use of an increased concentration of carboxylic acid.Moreover, decreasing the concentration of hydrogen peroxide maynecessitate the use of some stabilizing agent to ensure that thecomposition of the present invention will remain stable and efficaciousover the intended time period.

[0041] In all, altering the concentration of the oxidizing agent willeffect the equilibrium mix of the peroxycarboxylic acid used in theinvention.

The Carrier

[0042] The composition of the invention also includes a carrier. Thecarrier functions to provide a reaction medium for the solubilization ofconstituents and the production of peroxycarboxylic acid as well as amedium for the development of an equilibrium mixture of oxidizer,peroxycarboxylic acid, and carboxylic acid. The carrier also functionsto deliver and wet the antimicrobial composition of the invention to theintended substrate. To this end, the carrier may contain any componentor components which will facilitate the functions. Generally, thecarrier consists of water which is an excellent solubilizer and mediumfor reaction and equilibrium. The carrier may also include any number ofconstituents such as various organic compounds which facilitate thefunctions provided above. Organic solvents which have been found usefulinclude simple alkyl alcohols such as ethanol, isopropanol, n-propanol,and the like. Polyols are also useful carriers in accordance with theinvention, including propylene glycol, polyethyleneglycol, glycerol,sorbitol, and the like. Any of these compounds may be used singly or incombination with other organic or inorganic constituents or, incombination with water or in mixtures thereof. Preferably, the carrierconsists of from about 1 wt-% to about 60 wt-% of an organic solvent.

[0043] Generally, the carrier makes up a large portion of thecomposition of the invention and may essentially be the balance of thecomposition apart from the active antimicrobial composition adjuvants,and the like. Here again, the carrier concentration and type will dependupon the nature of the composition as a whole, the environmental storageand method of application including concentration of the antimicrobialagent, among other factors. Notably the carrier should be chosen andused at a concentration which does not inhibit the antimicrobialefficacy of the act in the composition of the invention.

[0044] B. Adjuvants

[0045] The composition of the invention may also optionally include anynumber of adjuvants which are stable in an oxidizing environment, andadd beneficial properties of stability, sequestration, sheeting andrinsing, etc. These adjuvants may be preformulated with the sanitizingagent of the invention or added to the system simultaneously, or evenafter, the addition of the sanitizing agent of the invention.

Chelating Agent

[0046] The sanitizing agents of the invention may also contain apolyvalent metal complexing or chelating agent that aids in reducing theharmful effects of hardness components and service water and improvesproduct stability. The typically harmful effects of calcium, magnesium,iron, manganese, etc., ions present in service water can interfere withthe action of either the washing compositions or rinsing compositions orcan tend to decompose the active peroxygen sanitizer materials. Thechelating agent or sequestering agent can effectively complex and removesuch ions from inappropriate interaction with active ingredients thusincreasing sanitizing agent performance.

[0047] Both organic and inorganic chelating agents may be used.Inorganic chelating agents include such compounds as sodiumtripolyphosphate and other higher linear and cyclic polyphosphatespecies. Organic chelating agents include both polymeric and smallmolecule chelating agents. Polymeric chelating agents commonly comprisepolyanionic compositions such as polyacrylic acid compounds. Aminophosphates and phosphonates are also suitable for use as chelatingagents in the compositions of the invention and include ethylene diamine(tetramethylene phosphonates), nitrilotrismethylene phosphates,diethylenetriamine (pentamethylene phosphonates). These aminophosphonates commonly contain alkyl or alkaline groups with less than 8carbon atoms.

[0048] Preferred chelating agents for use in this invention includeimproved food additive chelating agents such as disodium salts ofethylene diamine tetraacetic acid or the well known phosphonates sold inthe form of DEQUEST® materials, for example,1-hydroxyethylidene-1,1-diphosphonic acid, etc. The phosphonic acid mayalso comprise a low molecular weight phosphonopolycarboxylic acid suchas one having about 2-4 carboxylic acid moieties and about 1-3phosphonic acid groups. Such acids include 1-phosphono-1-methylsuccinicacid, phosphonosuccinic acid and 2-phosphonobutane-1,2,4-tricarboxylicacid. Another organic phosphonic acid is (CH₃C(PO₃H₂)₂OH), availablefrom Monsanto Industrial Chemicals Co., St Louis, Mo., as DEQUEST® 2010,(which is a 58-62% aqueous solution; amino [tri(methylenephosphonicacid)] (N[CH₂PO₃H₂]₃), available from Monsanto as DEQUEST® 2000, as a50% aqueous solution; ethylenediamine [tetra(methylenephosphonic acid)]available from Monsanto as DEQUEST® 2041, as a 90% solid acid product;and 2-phosphonobutane-1,2,4-tricarboxylic acid available from MobayChemical Corporation, Inorganic Chemicals Division, Pittsburgh, Pa., asBayhibit AM, as a 45-50% aqueous solution.

[0049] The above-mentioned phosphonic acids can also be used in the formof water soluble acid salts, particularly the alkali metal salts, suchas sodium or potassium; the ammonium salts or the alkylol amine saltswhere the alkylol has 2 to 3 carbon atoms, such as mono-, di-, ortriethanolamine salts. If desired, mixtures of the individual phosphonicacids or their acid salts can also be used.

[0050] The concentration of chelating agent useful in the presentinvention generally ranges from about 0.01 to about 10 wt-%, preferablyfrom about 0.1 to about 5 wt-%, most preferably from about 0.5 to about2 wt-%.

Hydrotrope

[0051] The sanitizing agent of the invention may also include ahydrotrope coupler or solubilizer. Such materials can be used to ensurethat the composition remains phase stable and in a single highly activeaqueous form. Such hydrotrope solubilizers or couplers can be used atcompositions which maintain phase stability but do not result inunwanted compositional interaction.

[0052] Representative classes of hydrotrope solubilizers or couplingagents include an anionic surfactant such as an alkyl sulfate, an alkylor alkane sulfonate, a linear alkyl benzene or naphthalene sulfonate, asecondary alkane sulfonate, alkyl ether sulfate or sulfonate, an alkylphosphate or phosphonate, dialkyl sulfosuccinic acid ester, sugar esters(e.g., sorbitan esters) and a C₈₋₁₀ alkyl glucoside.

[0053] Preferred coupling agents for use in the rinse agents of theinvention include n-octane sulfonate and aromatic sulfonates such as analkyl benzene sulfonate (e.g., sodium xylene sulfonate or naphthalenesulfonate). Many hydrotrope solubilizers independently exhibit somedegree of antimicrobial activity at low pH. Such action adds to theefficacy of the invention but is not a primary criterion used inselecting an appropriate solubilizing agent. Since the presence of theperoxycarboxylic acid material in the proteinated neutral state providesbeneficial biocidal or sanitizing activity, the coupling agent should beselected not for its independent antimicrobial activity but for itsability to provide effective single phase composition stability in thepresence of substantially insoluble peroxycarboxylic acid materials andthe more soluble compositions of the invention. Generally, any number ofsurfactants may be used consistent with the purpose of this constituent.

[0054] Anionic surfactants useful with the invention include alkylcarboxylates, linear alkylbenzene sulfonates, paraffin sulfonates andsecondary n-alkane sulfonates, sulfosuccinate esters and sulfated linearalcohols.

[0055] Zwitterionic or amphoteric surfactants useful with the inventioninclude β-N-alkylaminopropionic acids, n-alkyl-β-iminodipropionic acids,imidazoline carboxylates, n-alky-Iletaines, amine oxides, sulfobetainesand sultaines.

[0056] Nonionic surfactants useful in the context of this invention aregenerally polyether (also known as polyalkylene oxide, polyoxyalkyleneor polyalkylene glycol) compounds. More particularly, the polyethercompounds are generally polyoxypropylene or polyoxyethylene glycolcompounds. Typically, the surfactants useful in the context of thisinvention are synthetic organic polyoxypropylene (PO)-polyoxyethylene(EO) block copolymers. These surfactants have a diblock polymercomprising an EO block and a PO block, a center block ofpolyoxypropylene units (PO), and having blocks of polyoxyethylene gratedonto the polyoxypropylene unit or a center block of EO with attached POblocks. Further, this surfactant can have further blocks. of eitherpolyoxyethylene or polyoxypropylene in the molecule. The averagemolecular weight of useful surfactants ranges from about 1000 to about40,000 and the weight percent content of ethylene oxide ranges fromabout 10-80% by weight.

[0057] Also useful in the context of this invention are surfactantsincluding alcohol alkoxylates having EO, PO and BO blocks. Straightchain primary aliphatic alcohol alkoxylates can be particularly usefulas sheeting agents. Such alkoxylates are also available from severalsources including BASF Wyandotte where they are known as “Plurafac”surfactants. A particular group of alcohol alkoxylates found to beuseful are those having the general formula R-(EO)_(m)-(PO)_(n) whereinm is an integer of about 2-10 and n is an integer from about 2-20. R canbe any suitable radical such as a straight chain alkyl group having fromabout 6-20 carbon atoms.

[0058] Other useful nonionic surfactants of the invention include cappedaliphatic alcohol alkoxylates. These end caps include but are notlimited to methyl, ethyl, propyl, butyl, benzyl and chlorine.Preferably, such surfactants have a molecular weight of about 400 to10,000. Capping improves the compatibility between the nonionic and theoxidizers hydrogen peroxide and peroxycarboxylic acid, when formulatedinto a single composition. Other useful nonionic surfactants arealkylpolyglycosides.

[0059] Another useful nonionic surfactant of the invention is a fattyacid alkoxylate wherein the surfactant comprises a fatty acid moietywith an ester group comprising a block of EO, a block of PO or a mixedblock or heteric group. The molecular weights of such surfactants rangefrom about 400 to about 10,000, a preferred surfactant has an EO contentof about 30 to 50 wt-% and wherein the fatty acid moiety contains fromabout 8 to about 18 carbon atoms.

[0060] Similarly, alkyl phenol alkoxylates have also been found usefulin the invention. Such surfactants can be made from an alkyl phenolmoiety having an alkyl group with 4 to about 18 carbon atoms, cancontain an ethylene oxide block, a propylene oxide block or a mixedethylene oxide, propylene oxide block or heteric polymer moiety.Preferably such surfactants have a molecular weight of about 400 toabout 10,000 and have from about 5 to about 20 units of ethylene oxide,propylene oxide or mixtures thereof.

[0061] The concentration of hydrotrope useful in the present inventiongenerally ranges from about 0.1 to about 20 wt-%, preferably from about0.5 to about 10 wt-%, most preferably from about 1 to about 4 wt-%.

Thickening/Gelling Agents

[0062] Thickeners useful in the present invention are those which do notleave contaminating residue on the surface of application, i.e.,constituents which are incompatible with food or other sensitiveproducts in contact areas.

[0063] Generally, thickeners which may be used in the present inventioninclude natural gums such as xanthan gum. Also useful in the presentinvention are cellulosic polymers, such as carboxymethyl cellulose.Generally, the concentration of thickener use in the present inventionwill be dictated by the desired viscosity within the final composition.However, as a general guideline, viscosity of thickener within thepresent composition ranges from about 0.1 wt-% to about 1.5 wt-%,preferably from about 0.1 wt-% to about 1.0 wt-%, and most preferablyfrom about 0.1 wt-% to about 0.5 wt-%.

[0064] C. Formulation

[0065] The compositions of the invention can be formulated by combiningthe sanitizing agent materials including other adjuvant components withthe materials that form the sanitizer composition, the carboxylic acidor acid blend, hydrogen peroxide and optionally, hydrotrope solubilizer.

[0066] The compositions can also be formulated with preformedperoxycarboxylic acids. The preferred compositions of the invention canbe made by mixing the carboxylic acid or mixture thereof with anoptional hydrotrope solubilizer or coupler, reacting the mixture withhydrogen peroxide and then adding the balance of required ingredients toprovide rinsing and sanitizing action.

[0067] A stable equilibrium mixture is produced containing thecarboxylic acid or blend with hydrogen peroxide and allowing the mixtureto stand for 1-7 days at 15° C. or more. With this preparatory method,an equilibrium mixture will be formed containing an amount of hydrogenperoxide, unoxidized acid, oxidized or peroxycarboxylic acid andtypically unmodified couplers, solubilizer, or stabilizers.

[0068] D. Use Compositions

[0069] The invention contemplates a concentrate composition which isdiluted to a use solution prior to its utilization as a sanitizer.Primarily for reasons of economics, the concentrate would normally bemarketed and an end user would preferably dilute the concentrate withwater or an aqueous diluent to a use solution.

[0070] The general constituent concentrations of the sanitizingconcentrate formulated in accordance with the invention may be found inTable 1: TABLE 1 More Most Preferred Preferred Preferred Constituent(wt- %) (wt- %) (wt- %) H₂O₂   1-35  2-25  5-10 Peroxycarboxylic acids0.5-20  2-15  4-12 Carboxylic acid 0.5-60 10-60 20-50 Chelating agent0.01-10  0.01-5   0.5-2   Hydrotrope 0.1-20 0.5-10  1-4 Thickening agent 0.1-1.5 0.1-1.0 0.1-0.5 Carrier   0-97 10-90 12-65

[0071] The level of active components in the concentrate composition isdependent on the intended dilution factor and the desired activity ofthe peroxycarboxylic acid compound and the carboxylic acid.

[0072] Generally, a dilution of about 1 fluid ounce to about 0.5 to 10.0gallons of water is used for aqueous antimicrobial sanitizing solutions.The composition shown in the preferred column of the Table 1 above wouldbe used in a range from about 12.8 fluid ounce per gallon water to about1 fluid ounce per 780 gallons of water depending on the desired level ofperoxycarboxylic acid and concentration of the peroxycarboxylic acid inthe product concentrate.

[0073] Higher use dilutions can be employed if elevated use temperature(greater than 25° C.) or extended exposure time (greater than 30seconds) can be employed. In the typical use locus, the concentrate isdiluted with a major proportion of water and used for sanitizing usingcommonly available tap or service water mixing the materials at adilution ratio of about 0.1 to about 2 ounces of concentrate per gallonof water.

[0074] Aqueous antimicrobial sanitizing use solutions can include atleast about 2 ppm, preferably about 10 to about 500 ppm, and morepreferably about 100 to about 250 parts per million of theperoxycarboxylic acid material; about 20 ppm to about 10,000 ppm, andpreferably about 50 ppm to about 1,000 ppm of carboxylic acid; and about10 to about 1,000 ppm of hydrogen peroxide. The aqueous use solution canfurther include at least about 50 ppm, preferably about 500 ppm of thehydrotrope solubilizer, and have a pH in the use solution in the rangeof about 1 to about 11 preferably about 2 to about 10.

[0075] E. Method of Use

[0076] During processing of the carcass meat, the carcasses can becontacted with the compositions of the invention in any mode be thatinsures good contact between the carcass and the composition and atleast some minimal mechanical work to result in at least a one log₁₀reduction, preferably at least a two log₁₀ reduction and more preferablya three log₁₀ reduction in the resident microbial preparation. A fivelog₁₀ reduction in 30 seconds is a sanitizing treatment.

[0077] The invention is applicable to a wide range of possible animalcarcasses. For example, the antimicrobial compositions of the inventioncan be used on muscle meats including beef, pork, veal, buffalo or lamb,sea food including scallops, shrimp, crab, octopus, mussels, squid orlobster and poultry including chicken, turkey, ostrich, game hen, squabor pheasant.

[0078] A preferred mode is a pressure spray with the sanitizing solutionof the invention. During application of the spray solution on thecarcasses, the surface of the carcasses can be moved with mechanicalaction, preferably agitated, rubbed, brushed, etc. Agitation may be byphysical scrubbing of the carcasses, through the action of the spraysolution under pressure or by other means. The agitation increases theefficacy of the spray solution in killing micro-organism, perhaps due tobetter exposure of the solution into the crevasses or small coloniescontaining the micro-organisms. The spray solution, before application,may also be heated to a temperature of about 15 to 20° C., preferablyabout 20 to 50° C. to increase efficacy. After a sufficient amount oftime to kill the micro-organisms on the carcasses, the spray solutionmay be rinsed off the animal carcasses.

[0079] Application of the material by spray means can be accomplishedusing a manual spray wand application, an automatic spray of carcassesmoving along a production line using multiple spray heads to ensurecomplete contact or other spray means. One preferred automatic sprayapplication involves the use of a spray booth. The spray boothsubstantially confines the sprayed composition to within the parameterof the booth. The production line moves the carcass through the entrywayinto the spray booth in which the carcass is sprayed on all its exteriorsurfaces with sprays within the booth. After a complete coverage of thematerial and drainage of the material from the carcass within the booth,the carcass can then exit the booth in a fully treated form. The spraybooth can comprises steam jets that can be used to apply theantimicrobial compositions of the invention. These steam jets can beused in combination with cooling water to ensure that the treatmentreaching the carcass surface is less than 65° C., preferably less than60° C. The temperature of the spray on the carcass is important toensure that the carcass meat is not substantially altered (cooked) bythe temperature of the spray. The spray pattern can be virtually anyuseful spray pattern.

[0080] The spray can comprise a fogged material that leaves a foggingapparatus as a dispersion of fog particles in a continuous atmosphere.Such a spray has no defined pattern. The spray can have a pattern suchas a conical spray in which the angle between the perimeter of the sprayranges from less than 180° to about 5°. Other spray patterns can also beuseful. We have found that one preferred spray pattern involves a “fan”spray pattern in which the spray exits the spray head in a substantiallyplanar form and the angle between the extent of the planar spray fromedge to edge is about 20° or less, preferably about 15° or less. We havefound that such a spray is preferred due to the increased mechanicalaction and efficiency of antimicrobial composition add on to thecarcass. When such a narrow angle fan spray is used in a spray cabinetenclosure to treat the carcasses, we have found that the optimumdistance between the spray head and the carcass is less than about 100centimeters, preferably about 20 to 80 centimeters, most preferablyabout 30 to 50 centimeters. Such a configuration efficiently transfersantimicrobial material to the carcass for efficient reduction of themicrobial populations.

[0081] There are a number of parameters which need to be considered ifspraying is the application method of choice. The first parameter todetermine is the pressure at which the composition is sprayed onto thecarcass. While spray pressures as low as about 25 psi (gauge) can beused with some valuable results, a higher spray pressure, greater thanabout 25, 50, 100, 150 psi and more preferably greater than about 200psi, are effective in reducing the microbial populations due to themechanical action of the spray on the carcass surface and on themicrobial population remaining on the surface of the carcass. The sprayaction is best at temperatures less than 65° C. While a compositioncomprising lactic acid has been found to be most effective at lowpressure, it has been discovered that equal, if not greaterantimicrobial efficacy can be obtained by eliminating the lactic acidand merely increasing the spray application pressure. Further, ifincreased spray pressures are used, the antimicrobial composition can beapplied at lower temperatures, potentially resulting in substantialenergy savings. Of course there appears to be a relationship betweenapplication spray duration and antimicrobial efficacy. While spraydurations of as little as about 10 seconds can be used, it has beendiscovered that a preferred spray duration is from about 10 to about 30seconds. Without wishing to be limited by theory, the increasedantimicrobial efficacy resulting from the use of the higher spraypressures is believed to be due to an improvement in penetrating thesurface of the carcass, particularly an increased ability to reach intocreases and crevices on the surface of the carcass.

[0082] During processing of the carcass meat, the carcasses may also beimmersed into a tank containing a quantity of sanitizing solution. Thesanitizing solution is preferably agitated to increase the efficacy ofthe solution and the speed in which the solution kills micro-organismsattached to the carcasses. Agitation can be obtained throughconventional means including through ultrasonic means, aeration bybubbling air through the solution or by mechanical means, such asstrainers, paddles, brushes, or pump driven liquid jets. The sanitizingsolution may also be heated to increase the efficacy of the solution inkilling micro-organisms. It is preferable that the carcasses be immersedin the sanitizing solution after the carcasses have been eviscerated andbefore any cooling process such as a chiller tank or a chill waterspray.

[0083] In another alternative embodiment of the present invention, thecarcasses may be treated with a foaming version of the composition. Thefoam may be prepared by mixing foaming surfactants with the sanitizingsolution at time of use. The foaming surfactants could be nonionic,anionic or cationic in nature. Examples of useful surfactant typesinclude, but not limited to the following: alcohol ethoxylates, alcoholethoxylate carboxylate, amine oxides, alkyl sulfates, alkyl ethersulfate, sulfonates, quaternary ammonium compounds, alkyl sarcosines,betaines and alkyl amides. The foaming surfactant is mixed at time ofuse with the sanitizing solution. Use solution levels of the foamingagents is from about 50 ppm to about 2.0 wt-%. At time of use,compressed air is injected into the mixture, then applied to the carcasssurface through a foam application device such as a tank foamer or anaspirated wall mounted foamer.

[0084] In another alternative embodiment of the present invention, thecarcasses may be treated with a thickened or gelled version of thecomposition. In the thickened or gelled state the sanitizing solutionremains in contact with the carcass surface for longer periods of time,thus increasing the antimicrobial efficacy. The thickened or gelledsolution will also adhere to vertical surfaces. The composition or thesanitizing solution may be thickened or gelled using existingtechnologies such as: xantham gum, polymeric thickeners, cellulosethickeners or the like. Rod micelle forming systems such as amine oxidesand anionic counter ions could also be used. The thickeners or gelforming agents can be used either in the concentrated product or mixingwith the sanitizing solution, at time of use. Typical use levels ofthickeners or gel agents range from about 100 ppm to about 10 wt-%.

[0085] In another alternative embodiment of the present invention, thecarcasses may be treated with an electrostatically charged spray of thesanitizing solution. The sanitizing solution can be spray applied as acharged droplets by using conventional electrostatic spray technologiesincluding inductively charged methodologies. As charged droplets, thesanitizing solution will be attracted to opposite or differentiallycharged surfaces such as the surface of the carcass. As a result, moresanitizing solution will be applied to the carcass surface and lesssolution will miss the intended target, commonly called over-spray. Thecharged droplets will also provide an evenly distributed solution layeron the carcass surface. The charged droplet size will range from about10 microns to about 500 microns.

[0086] In another alternative embodiment of the present invention, thecarcasses may be subjected to a vacuum treatment either before applyingthe sanitizing solution, during the application of the sanitizingsolution or after applying the sanitizing solution. When the carcass issubjected to a vacuum treatment in conjunction with the application ofthe sanitizing solution, the penetration of the sanitizing solution intothe carcass substructure is enhanced. As a result, antimicrobialefficacy is improved. The amount of vacuum utilized is from about 2inches of Mercury (″Hg) to about 29 inches of Mercury (″Hg).

[0087] In another alternative embodiment of the present invention, thecarcasses may be subjected to an activating light source followingapplication of the sanitizing solution. The activating light can improvethe antimicrobial efficacy of the sanitizing solution. The light sourcecan be ultraviolet, infrared or from the visible spectrum.

[0088] The antimicrobial or sanitizing step can optionally be combinedwith a thermal intervention process which occurs either before, duringor after the application of the antimicrobial composition. The thermalintervention process may employ hot water or dry heat. In the case of ahot water thermal process, the carcass is enclosed in a chamber atatmospheric pressure. The chamber is filled with condensing steam(finely divided liquid water) for a short duration, quickly vented, thencooled to prevent browning of the meat carcass. The duration of thesteam thermal process may be from about 5 seconds to about 30 seconds.The chamber temperature may reach from about 50° C. to about 93° C.Similarly with dry heat, the carcass is placed in a chamber into whichheated air isdirected The air is heated from about 65° C. to about 260°C. The carcass is allowed from about 5 to about 30 seconds contact timewith the heated air, the chamber is vented and the carcass is cooled.

WORKING EXAMPLES

[0089] The invention will now be described in more detail by referenceto the following working examples. The only proper construction of theseexamples is as nonlimiting, illustrative example showing variousformulations, stabilities, and applications of the invention. TestFormula #1 Material Weight Percent Deionized water 53.9 MixedPeroxycarboxylic acids¹ 4.75 Hydrogen Peroxide 6.9 Acetic Acid 25.0Octanoic Acid 3.5 Hydroxyethylidene-1,1-diphosphonic acid 0.95 SodiumOctane mixed Mono- and Di- 5.0 Sulfonate

Working Example #1

[0090] The objective of working example #1 was to determine if 0.5% and1.0% lactic acid alone and in combination with Test Formula #1 and/orsteam achieved a reduction in the bacterial flora present on prerigorbeef samples. An exposure time of 10 minutes was utilized for allapplications and testing was performed at 33° C.

[0091] Operating Procedure:

[0092] Sixteen prerigor beef samples were obtained and kept in a cooleruntil time of testing. Samples were aseptically divided in half Eightdifferent test treatments were utilized with four replicate pieces pertreatment with the exception of the steam +0.5% lactic acid treatmentwhich only had three replicate pieces. Two cores (4.3 cm diameter) weretaken from each replicate piece before and after treatment, combinedinto 99 mL of Phosphate Buffered Dilution water, stomached for 1 minutesand then serially diluted and plated using pour plate technique. TestProducts: 1. Test Formula #1 at 200 ppm Total Peracid 2. Test Formula #1at 200 ppm Total Peracid + 0.5% Lactic Acid 3. Test Formula #1 at 200ppm Total Peracid + 1.0% Lactic Acid 4. 0.5% Lactic Acid 5. Steam Alone,followed by a sterile water rinse 6. Steam + Test Formula #1 at 200 ppmTotal Peracid, followed by a sterile water rinse 7. Steam + Test Formula#1 at 200 ppm Total Peracid + 0.5% Lactic Acid, followed by a sterilewater rinse 8. Steam + 0.5% Lactic Acid followed by a sterile waterrinse

[0093] Peracid Product Titrated Actual Titrated Peracid Test Formula #1at 200 ppm 212 ppm 200 ppm Test Formula #1 + 0.5% Lactic Acid 220 ppm200 ppm Test Formula #1 + 1.0% Lactic Acid 192 ppm Test Formula #1 +Steam 210 ppm Test Formula #1 + 0.5% Lactic Acid + Steam 220 ppm

[0094] Product Application: All product use solutions were applied by aspray application for 10 seconds. This delivered approxi- mately 150 mLof product. An exposure time of 10 minutes was utilized, followed by a10 second sterile water rinse, if applicable. Neutralizer: 99 mL ofPhosphate Buffered Dilution Water Dilutions Plated: 10⁰, 10⁻¹, 10⁻² forTotal Plate Count Before 10⁰, 10⁻¹ for Total Plate Count After PlatingMedium: Tryptone Glucose Extract Agar Incubation: 26° C. for 72 hours

[0095] Steam Application Parameters

Steam Alone 1st Replicate: Starting temperature was 86° C., ending at92° C. A 17 second exposure time was utilized and a 10 second delayoccurred prior to the sterile water rinse for 10 seconds. 2nd Replicate:Starting temperature was high 80° C., ending at 90 + ° C. 3rd & 4thReplicates: Starting temperature was 82° C., ending at 87° C. An 8second exposure time and a 10 second sterile water rinse were utilizedfor replicates 2, 3 and 4. Test Formula #1 + 1st Replicate: Startingtemperature was 82° C., Steam ending at 87° C. 2nd Replicate: Startingtemperature was 80° C., ending at 84° C. 3rd Replicate: Startingtemperature was 83° C., ending at 88° C. 4th Replicate: Startingtemperature was 86° C., ending at 89° C. An 8 second exposure time and a10 second sterile water rinse were utilized for all replicates. TestFormula #1 + 1st Replicate: Starting temperature was 88° C., 0.5% LacticAcid + ending at 91.5° C. Steam 2nd Replicate: Starting temperature was86.7° C., ending at 90 + ?° C. 3rd and 4th Replicates: Temperatures werenot recorded. An 8 second exposure time and a 10 second sterile waterrinse utilized for all repli- cates. 0.5% Lactic Acid + 1st Replicate:Starting temperature was 84° C., Steam ending at 88° C. 2nd Replicate:Starting temperature was not recorded, however the ending temperaturewas 91° C. 3rd Replicate: Temperatures were not recorded. An 8 secondexposure time and a 10 second sterile water rinse were utilized for allreplicates.

[0096] uz,11/22 Total Plate Count Results

Test Formula #1 3.3 × 10⁴ 7.7 × 10³ .80 at 200 ppm Test Formula #1 2.0 ×10⁵ 1.7 × 10⁴ 1.08 at 200 ppm + 0.5% Lactic Acid Test Formula #1 4.4 ×10⁴ 1.2 × 10³ 1.31 at 200 ppm + 1.0% Lactic Acid 0.5% Lactic 2.7 × 10⁴5.4 × 10³ 0.91 Acid Steam Alone 1.2 × 10⁴ 2.4 × 10³ 1.10 with SterileWater Rinse Steam + Test 1.5 × 10⁴ 8.4 × 10² 1.51 Formula #1 at 200 ppmwith Sterile Water Rinse Steam + Test Formula #1 3.1 × 10⁵ 2.6 × 10³2.55 at 200 ppm + 0.5% Lactic Acid With Sterile Water Rinse Steam + 0.5%Lactic 2.5 × 10⁴ 9.3 × 10² 1.69 Acid with Sterile Water Rinse

[0097] Conclusions:

[0098] The application of Steam with Test Formula #1 at 200 ppm incombination with 0.5% Lactic Acid outperformed all other treatments byachieving an average of a 2.55 log₁₀ reduction on the surface ofprerigor meat. Steam alone, provided an average 1.10 log₁₀ reductionwith temperatures ranging from 80-92° C. Test Formula #1 at 200 ppm incombination with 0.5% Lactic Acid only provided an average 1.10 log₁₀reduction in comparison to an average 1.31 log₁₀ reduction incombination with 1.0% Lactic Acid.

[0099] The purpose of the remaining working examples was to determine ifthe use of higher spray pressures, particularly those above 100 psi,would increase the antimicrobial efficacy of the compositions of theinvention.

Working Example #2

[0100] The objective of the testing was to determine the efficacy ofvarious antimicrobial treatments with extended spray and exposure timesagainst the bacterial flora of prerigor beef.

[0101] Test Method/Parameters:

[0102] Prerigor beef samples were obtained and kept in a cooler atambient temperature until time of testing. Ten different test treatmentswere utilized with four replicates per treatment Two cores (43 cmdiameter) were taken as each replicate from one piece for both before-and after-treatment samples and combined into 99 mL of Letheen Broth Thecores/neutralizer mixture were stomached for 1 minute and then seriallydiluted and plated using pour plate technique. Test Products: TestFormula #1* at 200 ppm Peracid = 0.42% (4.2 mL were added to 995.8 mLtap water) Test Formula #1* at 500 ppm Peracid (10.5 mL were added to989.5 mL tap water) 0.5% Lactic Acid * Test Formula #1, batch#Si120972,was titrated at 4.76% total peracid. Application: Eight cores (2 coresper replicate) were placed onto a clean and sanitary screen. The coreswere sprayed with the appropriate test product utilizing a 10- or 30-second spray application time. For each replicate, two cores wereremoved after a 10-minute exposure time and placed into a stomacher bagcontaining 99 mL of neutralizer. Neutralizer: 99 mL Letheen BrothDilutions: 10⁰, 10⁻¹, 10⁻² for Total Plate Count Before 10⁰, 10⁻¹ forTotal Plate Count After Plating Medium: Tryptone Glucose Extract AgarIncubation: 26° C. for 72 hours Calculations: Average CFU/plate = (Alleight counts from four replicates/4) Average CFU/plate × 100 = AverageCFU/100 mL = Y${{Average}\frac{CFU}{{cm}^{2}}} = \frac{Y}{2{\pi r}^{2}}$

Dilution = 10, 100, or 1000 r = 2.15 cm 2 = # of cores

[0103]

Water Control 3.6 × 10⁴ 4.7 × 10⁴ 0.05 98° F. 25 psi pressure, 10 sec.spray Water Control 1.2 × 10⁵ 1.9 × 10⁵ −0.21 120° 50 psi pressure, 30sec. spray 0.5% Lactic Acid 1.6 × 10⁴ 1.5 × 10⁴ −0.01 98° F. 25 psipressure, 10 sec spray 0.5% Lactic Acid 1.0 × 10⁵ 8.4 × 10⁴ 0.07 120° F.25 psi pressure, 10 sec. spray Test Formula #1 at 200 ppm 2.3 × 10⁴ 8.7× 10³ 0.41 Peracid 90° F. 50 psi pressure, 10 sec spray Test Formula #1at 200 ppm 1.5 × 10⁵ 1.6 × 10⁴ 0.97 Peracid 120° F. 50 psi pressure, 10sec spray Test Formula #1 at 200 ppm 9.0 × 10⁴ 3.9 × 10⁴ 0.37 Peracid120° F. 50 psi pressure, 30 sec spray Test Formula #1 at 200 ppm 6.5 ×10⁵ 6.4 × 10⁵ 0.01 Peracid  1.9 × 10⁴* 1.65* 120° 25 psi pressure, 30sec spray Test Formula #1 at 500 ppm 4.5 × 10⁴ 5.3 × 10³ 0.93 Peracid98° F. 25 psi pressure, 30 sec. spray Test Formula #1 at 500 ppm 4.9 ×10⁴ 1.1 × 10⁴ 0.67 Peracid 120° F. 25 psi pressure, 10 sec. spray

[0104] Conclusions:

[0105] Overall, the highest reductions in the bacteria flora on thesurface of prerigor beef were seen with the following treatments:

[0106] Test Formula #1 at 200 ppm total peracid at 50 psi pressure witha 10-second spray time at 120° F. achieved an average 0.97 log₁₀reduction.

[0107] Test Formula #1 at 500 ppm total peracid at 25 psi pressure witha 30-second spray at 98° F. achieved an average 0.93 log₁₀ reduction.

[0108] In regard to temperature, 120° F. resulted in higher efficacywith Test Formula #1 at 200 ppm total peracid at 50 psi pressure with a10-second spray time, with a 0.97 log₁₀ reduction versus a 0.41 log₁₀reduction at 98° F.

Working Example #3

[0109] The objective of the testing was to determine the efficacy ofTest Formula #1 at 200 ppm total peracid with a high pressureapplication spray at 100° F. against the bacterial flora of prerigorbeef.

[0110] Test Method/Parameters:

[0111] Prerigor beef samples were obtained and kept in a cooler atambient temperature until time of testing. Four different testtreatments were utilized with four replicates per treatment. Two cores(4.3 cm diameter) were 1 as each replicate from one piece for bothbefore and after treatment samples and combined into 99 mL of LetheenBroth. The cores/neutralizer mixtures were stomached for 1 minute andthen serially diluted and plated using pour plate technique. TestProduct: Test Formula #1 at 200 ppm total peracid (Batch # Si120972, wastitrated at 4.76% total peracid) Application: Eight cores (2 cores perreplicate) were aseptically removed from each sample before treatment.These were used for the before treatment samples. The remaining samplewas placed onto a clean and sanitary screen. The sample was then sprayedwith Vortex at approximately 200 ppm total peracid utilizing a 5-, 10-or 30- second spray application time. For each replicate, two cores wereremoved after a 10-minute exposure time and placed into a stomacher bagcontaining 99 mL of neutralizer. Neutralizer: 99 mL Letheen BrothDilutions: 10⁰, 10⁻¹, 10⁻² for Total Plate Count Before 10⁰, 10⁻¹ forTotal Plate Count After Plating Medium: Tryptone Glucose Extract AgarIncubation: 26° C. for 72 hours Calculations: Average CFU/plate = (Alleight counts from four replicates/4) Average CFU/plate × 100 = AverageCFU/100 mL = Y${{Average}\frac{CFU}{{cm}^{2}}} = \frac{Y}{2{\pi r}^{2}}$

Dilution = 10, 100, or 1000 r = 2.15 cm 2 = # of cores

[0112]

Water Control ˜230 psi 5.6 × 10⁵ 2.7 × 10⁴ 1.31 pressure, 30 sec. sprayTest Formula #1 at 200 ppm ˜1.9 × 10⁶   ˜2.1 × 10⁵   ˜0.96 Peracid ˜230psi pressure, 10 sec spray Test Formula #1 at 200 ppm ˜2.8 × 10⁶   2.0 ×10⁵ 1.15 Peracid ˜230 psi pressure, 5 sec spray Test Formula #1 at 200ppm 2.1 × 10⁶ <100 >2.90 Peracid ˜230 psi pressure, 30 sec spray

[0113] Conclusions:

[0114] Test Formula #1 at 200 ppm peracid with a 30-second exposure timeutilizing a high-pressure spray of 230 psi at the nozzle with a distanceof approximately 75 cm achieved the highest reduction with <3.4 CFU/cm²surviving after a 10-minute exposure time at −110° F. Utilizing thisprocedure, a >2.90 log reduction was achieved.

Working Example #4

[0115] The objective of the testing was to determine the efficacy ofTest Formula #1 at approximately 50, 100 and 200 ppm total peracid witha high pressure application spray at elevated temperatures in comparisonto Lactic Acid against the bacterial flora of prerigor beef.

[0116] Test Method Parameters:

[0117] Prerigor beef samples were obtained and kept in a cooler atambient temperature until time of testing. Four different testtreatments were utilized with four replicates per treatment. Two cores(4.3 cm diameter) were taken as each replicate from one piece for bothbefore- and after-treatment samples and combined into 99 nL of LetheenBroth. The cores/neutralizer mixtures were stomached for 1 minute andthen serially diluted and plated using pour plate technique. TestProduct: Test Formula #1 at 50, 100 and 200 ppm total peracid LacticAcid (88% concentrate) (Batch # Sil20972, was titrated at 4.76% totalperacid) Application: Eight cores (2 cores per replicate) wereaseptically removed from each sample before treatment. These were usedfor the before-treatment samples. The remaining sample was placed onto aclean and sanitary screen. The sample was then sprayed with Test Formula#1 at approximately 50, 100 or 200 ppm total peracid utilizing a 20- or30-second spray application time. 0.5% Lactic Acid utilized only the30-second spray application time. For each replicate, two cores wereremoved after a 10-minute exposure time and placed into a stomacher bagcontaining 99 mL of neutralizer. Neutralizer-. 99 mL Letheen BrothDilutions: 10⁰, 10⁻¹, 10⁻² for Total Plate Count before 10⁰, 10⁻¹ forTotal Plate Count After Plating Medium: Tryptone Glucose Extract AgarIncubation: 16° C. for 72 hours Calculations: Average CFU/plate = (Alleight counts from four replicates/4) Average CFU/plate × 100 = AverageCFU/100 mL = Y${{Average}\frac{CFU}{{cm}^{2}}} = \frac{Y}{2{\pi r}^{2}}$

Dilution = 10, 100 or 10000 r = 2.15 cm 2 = # of cores

[0118]

Test Formula #1 at 200 ppm 3.7 × 10⁴ <100 >2.58 Peracid ˜230 psipressure, 30 sec. spray Test Formula #1 at 200 ppm 3.1 × 10⁵ 3.3 × 10³2.00 Peracid ˜230 psi pressure 20 sec. spray Test Formula #1 at 100 ppm1.3 × 10⁶ 7.9 × 10³ 2.22 Peracid ˜230 psi pressure, 30 sec. spray TestFormula #1 at 100 ppm 2.0 × 10⁵ 4.3 × 10² 2.66 Peracid ˜230 psi pressure20 sec. spray Test Formula #1 at 50 ppm 3.1 × 10⁵ 6.3 × 10³ 1.70 Peracid˜230 psi pressure, 30 sec spray Test Formula #1 at 200 ppm 2.1 × 10⁵ 8.7× 10⁴ 0.38 Peracid ˜65 psi pressure 30 sec. spray ˜0.5% Lactic Acid ˜230psi 8.7 × 10⁵ 2.3 × 10⁴ 1.58 pressure, 30 sec. spray

[0119] Conclusions:

[0120] Test Formula #1 at 200 ppm total peracid sprayed for 30 secondsat ˜230 psi pressure achieved the highest reduction of bacteria presenton the surface of prerigor meat with a >2.58 log₁₀ reuction Test Formula#1 at 200 ppm sprayed for 30 seconds at ˜65 psi pressure only achievedan average 0.38 log₁₀ reduction.

Working Example #5

[0121] The objective of the testing was to determine the efficacy ofTest Formula #1 and Lactic Acid against Listeria innocua ATCC 33090 witha high-pressure application spray at elevated temperatures.

[0122] Test Method/Parameters:

[0123] Prerigor beef samples were obtained and kept in a cooler atambient temperature until time of testing. Samples were cut into 13 cmpieces and 2.0 mL of the inoculum (see Test System Preparation below)was spread evenly over the entire surface of the sample. Inoculatedsamples were then left at room temperature (˜23° C.) for ≧15 minutes.Four replicate samples were taken (two cores per replicate) beforetreatment After each spray treatment, a 10-minute exposure time wasutilized, and tahen four replicate samples were taken (two cores perreplicate) and stomached for 1 minute, serially diluted and plated usingpour plate technique.

[0124] Treatments:

[0125] 1. Test Formula #1 at 200 ppm total peracid with psi pressurespray, 30 second spray time.

[0126] 2. Test Formula #1 at 200 ppm total peracid with -150 psipressure spray, 30 second spray time.

[0127] 3. Test Formula #1 at 200 ppm total peracid with -100 psipressure spray, 30 second spray time.

[0128] 4. Water Control with ˜220 psi pressure spray, 30-second spraytime.

[0129] 5. ˜0.5%-0.75% Lactic Acid with -220 psi pressure spray,30-second spray time.

[0130] 6. Test Formula #1 at 100 ppm total peracid with ˜220 psipressure spray, 30 second spray time.

[0131] 7. Test Formula #1 at 200 ppm total peracid with ˜220 psipressure spray, 15 second spray time.

[0132] *Tiration of the Lactic Acid solution used 12 drops of 1N SodiumHydroxide for the indicator color change. In preliminary titrations of a0.5% Lactic Acid solution, 7 drops of 1N Sodium Hydroxide were needed.Therefore, the sample was estimated to be at a concentration between0175% and 1.0% Lactic Acid. Test Temperature: ˜120° F. Test System:Listeria innocua ATCC 33090 Test System 25 grams of sterilized cow feceswas added into Preparation: 50 grams of sterile phosphate buffereddilution water and stomached for 1 minute. 60.0 grams from this fecalslurry was transferred to a sterile stomacher bag and 6.0 mL of an ˜10⁸CFU/mL Listeria innocua 24-hour broth culture (grown in BHI broth at 37°C.) was added and mixed. This inoculum was therefore estimated at 10⁷CFU/mL, which yielded approximately 10⁵ CFU/cm². Exposure Time: 10minutes Neutralizer: 99 mL Letheen Broth Dilutions: 10⁻⁴, 10⁻⁵, 10¹⁶(for Before Treatment, Inoculation Numbers samples) 10⁰, 10⁻¹, 10⁻²(After Treatment samples) Plating Medium: Listeria Selective AgarIncubation: 26° for 72 hours Calculations: Average CFU/plate = (Alleight counts from four replicates/4) Average CFU/plate × 100 = AverageCFU/100 mL = Y${{Average}\frac{CFU}{{cm}^{2}}} = \frac{Y}{2{\pi r}^{2}}$

r = 2.15 cm 2 = # of cores

[0133]

Test Formula #1 at 200 ppm 1.6 × 10⁵ 1.97 Peracid ˜220 psi pressure 30second spray* Test Formula #1 at 200 ppm 5.1 × 10⁴ 2.45 Peracid ˜150 psipressure 30 second spray* Test Formula #1 at 200 ppm 1.4 × 10⁵ 2.03Peracid ˜100 psi pressure 30 second spray* Water Control ˜220 psi 4.9 ×10⁵ 1.48 pressure 30 second spray Lactic Acid ˜220 psi 3.5 × 10⁵ 1.63pressure 30 second spray Test Formula #1 at 100 ppm 1.6 × 10⁵ 1.97Peracid ˜220 psi pressure 30 second spray* Test Formula #1 at 200 ppm2.2 × 10⁵ 1.83 Peracid ˜100 psi pressure 15 second spray*

[0134] Conclusions:

[0135] Treatment at 200 ppm peracid with an ˜150 psi spray for 30seconds achieved an average 2.45 log₁₀ reduction of Listeria innocuaATCC 33090. Lactic Acid achieved a 1.63 log₁₀ reduction of this organismwhich was only slightly higher than the water control which achieved anaverage 1.48 log₁₀ reduction.

[0136] The above discussion, examples, and data illustrate our currentunderstanding of the invention. However, since many variations of theinvention can be made without departing form the spirit and scope of theinvention, the invention resides in the claims hereinafter appended.

We claim:
 1. A method of treating an animal carcass to reduce amicrobial population in resulting cut meat, the method comprising thesteps of: (a) treating said carcass with an antimicrobial compositioncomprising: (i) an effective antimicrobial amount comprising at least 2ppm of one or more mono- or di-peroxycarboxylic acids having up to 12carbon atoms; and (ii) an effective antimicrobial amount comprising atleast 20 ppm of one or more carboxylic acids having up to 18 carbonatoms; and (b) reducing the microbial population.
 2. The method of claim1 wherein the population reduction comprises at least one log₁₀reduction in the microbial population.
 3. The method of claim 1 whereinthe population reduction comprises at least two log10 reduction in themicrobial population.
 4. The method of claim 1 wherein the populationreduction comprises at least three log₁₀ reduction in the microbialpopulation.
 5. The process of claim 2 wherein the population comprises ahuman pathogen.
 6. The process of claim 4 wherein the populationcomprises Escherichia coli.
 7. The method of claim 1 wherein the carcassis selected from a muscle meat including beef, pork, veal, buffalo orlamb.
 8. The method of claim 1 wherein the carcass is sea food includingscallops, shrimp, crab, octopus, mussels, squid or lobster.
 9. Themethod of claim 1 wherein the carcass is poultry including chicken,turkey, ostrich, game hen, squab or pheasant.
 10. The method of claim 1wherein the peroxycarboxylic acid comprises one or more peroxycarboxylicacids having from 2 to 4 carbon atoms and a peroxycarboxylic acid havingfrom 8 to 12 carbon atoms.
 11. The method of claim 7 wherein theperoxycarboxylic acid comprises peroxyacetic acid and peroxyoctanoic orperoxydecanoic acid, or mixtures thereof.
 12. The method of claim 10wherein the peroxycarboxylic acid having from 2 to 4 carbon atoms isperoxyacetic acid and the peroxycarboxylic acid having from 8 to 12carbon atoms is peroxyoctanoic acid resulting in a ratio of about 10 toabout 1 parts by weight of peroxyacetic acid per each 1 part ofcarboxylic acid.
 13. The method of claim 1 wherein the carboxylic acidis acetic acid.
 14. The method of claim 1 wherein the carboxylic acid isan alpha-hydroxy mono or dicarboxylic acid having from 3 to 6 carbonatoms.
 15. The method of claim 14 wherein the carboxylic acid is lacticacid.
 16. The method of claim 1 wherein said antimicrobial compositioncomprises about 2 to 25 parts by weight of hydrogen peroxide per eachone million parts of the composition.
 17. The method of claim 1 whereinsaid antimicrobial composition is applied to the carcass by means of aspray.
 18. The method of claim 1 wherein said antimicrobial compositionis applied to the carcass by means of a fog.
 19. The method of claim 1wherein said antimicrobial composition is applied to the carcass bymeans of a foam.
 20. The method of claim 1 wherein said antimicrobialcomposition is applied to the carcass by applying in the form of athickened or gelled solution.
 21. The method of claim 1 wherein all orpart of the carcass is dipped in said antimicrobial composition.
 22. Themethod of claim 21 wherein a solution comprising the antimicrobialcomposition is agitated.
 23. The method of claim 1 which furtherincludes a vacuum treatment step.
 24. The method of claim 1 whichfurther includes the step of applying an activated light source to saidcarcass.
 25. An antimicrobial composition adapted for cleaning andsanitizing animal carcases comprising: (a) about 0.5 wt-% to about 20wt-% of a mixture of one or more peroxycarboxylic acids having from 2 to4 carbon atoms and one or more peroxycarboxylic acids having from 8 to12 carbon atoms; (b) from about 0.5 wt-% to about 60 wt-% of analpha-hydroxy mono or dicarboxylic acid having from 3 to 6 carbon atoms(c) an effective amount of a sequestrant; and (d) an effective amount ofa hydrotrope.
 26. The composition of claim 25 wherein theperoxycarboxylic acid is a mixture of peroxyacetic acid andperoxyoctanoic or peroxydecanoic acid.
 27. The composition of claim 26wherein the peroxycarboxylic acid is a mixture of peroxyacetic acid andperoxyoctanoic acid in a ratio of about 10:1 to about 1:1.
 28. Thecomposition of claim 25 wherein the alpha-hydroxy mono- or dicarboxylicacid is lactic acid.
 29. The composition of claim 25 which furthercomprises about 1 wt-% to about 35 wt-% of hydrogen peroxide.
 30. Thecomposition of claim 25 which further comprises from about 0.01 wt-% toabout 10 wt-% of a sequestering agent.
 31. The composition of claim 30wherein the sequestering agent is 1-hydroxyethylidene-1,1-diphosphonicacid.
 32. The composition of claim 25 which further comprises from about0.1 to about 20 wt-% of a hydrotrope.
 33. The composition of claim 25which further comprises from about 0.01 to about 10 wt-% of a thickeningor gelling agent.
 34. The composition of claim 25 which furthercomprises from about 1 to about 60 wt-% of an organic solvent.
 35. Anantimicrobial composition adapted for treating animal carcassesconsisting essentially of: (a) a mixture of peroxyacetic andperoxyoctanoic acid in a ratio of about 10:1 to about 1:1; (b) fromabout 0.1 wt-% to about 10 wt-% of lactic acid; (c) from about 4 wt-% toabout 10 wt-% of hydrogen peroxide; and (d) from about 0.5 wt-% to about1.5 wt-% of a sequestering agent.
 36. The composition of claim 35wherein the sequestering agent is the sequestering agent is1-hydroxyethylidene-1,1-diphosphonic acid.
 37. A method of treating ananimal carcass to reduce a microbial population in resulting cut meat,the method comprising the steps of: (a) spraying an aqueousantimicrobial treatment composition onto said carcass at a pressure ofat least 50 psi at a temperature of up to about 60° C. resulting in acontact time of at least 30 seconds, the antimicrobial compositioncomprising an effective antimicrobial amount comprising least 2 ppm ofone or more carboxylic acid, peroxycarboxylic acid or mixtures thereof;and (b) achieving at least a one log₁₀ reduction in the microbialpopulation.
 38. The method of claim 37 wherein the antimicrobialcomposition comprises an effective antimicrobial amount comprising atleast 2 ppm of one or more peroxycarboxylic acids having up to 12 carbonatoms; and at least 20 parts of one or more carboxylic acids having upto 18 carbon atoms.
 39. The method of claim 37 wherein theperoxycarboxylic acid comprises peroxyacetic acid, peroxyoctanoic acid,peroxydecanoic acid or mixtures thereof.
 40. The method of claim 37wherein the carboxylic acid comprises acetic acid, lactic acid ormixtures thereof.
 41. The method of claim 37 wherein the antimicrobialcomposition comprises at least about 5 wt % hydrogen peroxide.
 42. Themethod of claim 37 wherein the antimicrobial compositions are applied bymeans of an electrostatically accelerated spray.
 43. A method oftreating an animal carcass to reduce a microbial population in resultingcut meat, the method comprising the steps of: placing the carcass in achamber at atmospheric pressure; filling the chamber with condensingsteam comprising an antimicrobial composition for a short duration; andquickly venting and cooling the chamber to prevent browning of the meatcarcass; wherein the duration of the steam thermal process may be fromabout 5 seconds to about 30 seconds and the chamber temperature mayreach from about 50° C. to about 93° C.
 44. The method of claim 43wherein the antimicrobial composition comprises an effectiveantimicrobial amount comprising at least 2 ppm of one or moreperoxycarboxylic acids having up to 12 carbon atoms; and at least 20parts of one or more carboxylic acids having up to 18 carbon atoms. 45.The method of claim 44 wherein the peroxycarboxylic acid comprisesperoxyacetic acid, peroxyoctanoic acid, peroxydecanoic acid or mixturesthereof.
 46. The method of claim 44 wherein the carboxylic acidcomprises acetic acid, lactic acid or mixtures thereof.
 47. The methodof claim 44 wherein the antimicrobial composition comprises at leastabout 5 wt % hydrogen peroxide.
 48. The method of claim 44 wherein theantimicrobial compositions are applied by means of an electrostaticallyaccelerated spray.